Additives for improving the electrical properties of hydrocarbon oils



United States Patent fiice 2,974,027 Patented Mar. 7, 196i ADDITIVES FORIMPROVING THE ELECTRICAL PROPERTIES OF HYDROCARBON OILS James T. DiPiazza, Mountainside, N .J., assignor to Esso Research and EngineeringCompany, a corporation of Delaware No Drawing. Filed Oct. 6, 1958, Ser.No. 765,306

15 Claims. (Cl. 52-6) tolerance and rust inhibiting action by theincorporation therein of tetra-aliphatic ammonium salts of certaincarboxylic acids in combination with certain acidic compounds selectedfrom the class of alkyl acid phosphates and alkyl mercapto acetic acids.

The electrical properties of hydrocarbon oils boiling in the rangebetween about 75 F. and about 750 F. have assumed increasing importancein recent years as a result of a series of explosions which haveoccurred during the transportation and handling of such oils. Strongevidence indicates that these explosions have been caused by thegeneration and accumulation of electrical charges within the oils untilelectrical discharges sufiicient to ignite hydrocarbon vapors inadmixture with air occurred. Such explosions have, for the most part,taken place as the oils were being transferred from one vessel intoanother and it is generally thought that the tribo-electrical propertiesof the oils were responsible.

Studies have shown that electrical charges are generated during thehandling of a wide variety of distillate petroleum products. Inlaboratory experiments it has been demonstrated that high voltagedischarges can be created during the pumping of hydrocarbons ranging inboiling range from about 75 F. up to about 750 F., as shown in thefollowing table.

T ABLE I Production of electrical discharges in laboratory pumping testsIn general, the higher boiling, more viscous products are moresusceptible to the generation of electrical charges than are the lowerboiling materials. Aviation turbo-jet fuels and certain solvents whichhave relatively low initial boiling points are particularly hazardous,however, because their volatility is such that their vapors formexplosive mixtures with air over a relatively 'wide temperature rangeand hence any discharge which occurs is likely to cause an explosion.

The actual mechanisms involved in the generation, accumulation anddischarge of electrical energy during the handling of hydrocarbons arenot fully understood. It is known, however, that the electricalconductivity of the hydrocarbons plays an important part in thisphenomenon. Increasing the conductivity increases the rate at whichcharges are dissipated and it therefore appears that the danger ofexplosions due to electrical discharges can be abated by increasingconductivity. In general, it has been found that hydrocarbons havingspecific conductivities in the range between about l 1O- and 1X10 mhosper centimeter are particularly hazardous and that the hazard is reducedif the conductivity of the oil is greater than about 1X10 mho percentimeter.

It'has been suggested heretofore that a variety of differentpolarcompounds be added to hydrocarbons to increase their specificconductivity and thus reduce the danger that an explosion due to thegeneration, accumulation and discharge of electrical energy in thehydrocarbons will occur. Certain metallic compounds, particularly soapsof polyvalent metals and combinations of such soaps with other polarcompounds, have been said to be particularly elfec-tive. In practice,however, it has been found that such additive materials of the prior artare of little value for improving the electrical properties ofhydrocarbons because they are readily extracted by small quantities ofwater with which the hydrocarbons come into contact and because theydegrade other properties of the hydrocarbons.

The present invention provides a new and improved class of additivecompositions for use in hydrocarbons boiling in the range between about75 F. and about 750 F. which greatly improve the electrical propertiesof such hydrocarbons and in addition are free of the undesirablefeatures which have characterized additives proposed for this serviceheretofore. In accordance with the invention, it has now been found thattetra-aliphatic ammonium salts of certain carboxylic acids incombination with certain alkyl acid phosphates or alkyl mercapto aceticacids have a synergistic effect upon the electrical properties ofhydrocarbons and provide much greater protection against the generation,accumulation and discharge of electrical energy in such hydrocarbonsthan has been possible in the past. Moreover, it has been found thatthese synergistic additive combinations markedly improve the watertolerance of hydrocarbons to which they are added and are not extractedby water with which the hydrocarbons come into contact. A further a jadvantage of the additive combinations of the invention is that theyafford much greater protection against rust and corrosion of metals incontact with the fuels in the presence of water than do the 111stinhibitorsnow 'em The invention thus prou vides a new class ofmultifunctional additives which ployed in such hydrocarbons.

greatly improve the properties'of hydrocarbon oils and the like to whichthey are added.

The tetra-aliphatic ammonium salts of carboxylic acids which areemployed in the additive combinations of the invention aretetra-aliphatic ammonium salts of hydroxy carboxylic acids containingfrom 2 to. 10 carbon atoms in the acid portion of the molecule. Examplesof hydroxy carboxylic acids which maybe employed in .pre paring thesesalts include glycolic acid, lactic acid, hydracrylic acid,3-hydroxybutyric acid, 2-hydroxybutyric acid, l-hydroxybutyric acid,glyceric acid, erythric acid,"

arabitic acid, manniticacid, gluconic acid, galacturonic acid, tartronicacid, malic acid, tartaric acid, trihydroxyglutaric acid, saccharicacid, citric acid, mandelic acid, phenyllactic acid, tropic acid andgallic acid. The additives thus include tetra-aliphatic ammonium saltsof both aliphatic and cyclic hydroxy carboxylic acids containing from 2to 10 carbon atoms .per molecule. The acids must contain at least onehydroxy group as well as one carboxyl group. They may, however, containup to 5 .hydroxyl groups and up to 4 carboxyl groups. Salts of thealiphatic hydroxy carboxylic acids containing from 2 to 6 carbon atomsper molecule are preferred. Tetraaliphatie ammonium salts of malic acidand gluconic acid, wherein one hydroxyl group and one carboxyl group areattached to a carbon atom in common, have been found to be especiallyeffective and are therefore particularly preferred.

Tetra-aliphatic ammonium salts of the hydroxy carboxylic acids set forthabove may be readily prepared by reacting such acids withtetra-aliphatic ammonium hydroxides and then removing the resultingwater by means of an azeotropic distillation employing a solvent such asbenzene or toluene.

Tetra-aliphatic ammonium hydroxides suitable for use in the preparationof salts by the reaction set forth above are those having aliphaticgroups of from 1 to 24 carbon atoms in length. The aliphatic groups maybe either alkyl groups or alkenyl groups. Examples of suchtetraaliphatic ammonium hydroxides include tetrapropyl ammoniumhydroxide, ethyltributyl ammonium hydroxide, dimethyldibutenyl ammoniumhydroxide, butyltrihexyl ammonium hydroxide, dimethyldihexadecylammonium hydroxide, butyltrioleyl ammonium hydroxide, trimethylhexadecylammonium hydroxide, tetraheptadecyl arnmoniurn hydroxide and the like.Tetra-aliphatic ammom'um hydroxides containing alkyl and alkenylradicals such as those set forth above are widely available and theirproperties will be familiar to those skilled in the art.

Preferred tetra-aliphatic ammonium hydroxides for use in preparing thesalts of'hydroxy carboxylic acids which are employed as one constituentof the additive combinations of the invention are commercial mixtures ofsuch hydroxides derived from naturally-occurring materials such ascoconut oil, tallow fat and soy bean oil. One such mixture, for example,is trimethylsoya ammonium hydroxide, which is derived in part from soybean oil and contains about 8% C about 91% C and about 1% C aliphaticradicals in the soya group. Similar mixed compounds may be derived fromLorol alcohols, which are mixtures of primary alcohols containing from10 to 18 carbon atoms prepared by the hydrogenation of coconut oil. Suchmixed compounds are also sometimes referred to as coco alcohols.Tetra-aliphatic ammonium hydroxides having one or more such mixedaliphatic groups may be employed.

The alkyl acid phosphates which may be used as the second constituent ofthe additive combination of the invention are monoand dialkyl acidphosphates having alkyl groups of from about 6 to about 10 carbon atoms.Such acid phosphates are normally prepared by the reaction of P with analcohol or a mixture of alcohols. The resulting products may thuscontain mixed alkyl groups. Particularly preferred alkyl acid phosphatesfor use in accordance with the invention are those which are prepared bythe reaction of a C -oxo alcohol with phosphorus pentoxide. The C -oxoalcohols are mixed isoalkyl alcohols derived by the well known Oxoprocess, by catalytic reaction of a C copolymer of propylene and butenewith carbon monoxide and hydrogen to form aldehydes which are thenhydrogenated to alcohols. The copolymer normally consists of a mixtureof isomers because it is derived from a refinery gas stream containingpropylene and mixed normal and iso butylenes. The C -OXD alcohols arenow well known in the art. A more 4 complete description of them may befound in colums 4 and 5 of US. Patent 2,837,562.

The alkyl mercapto acetic acids which are also useful in combinationwith the tetraaliphatic ammonium salts of hydroxy carboxylic acid inaccordance with the invention are alkyl thioethers of acetic acid havingthe formula RSCH COOH where R is an alkyl group containing from about 4to about 20 carbon atoms, preferably from about 8 to about 18 carbonatoms. These compounds may be prepared by the reaction of an alkylalkali metal mercaptide with a haloacetic acid as described in US.Patent 2,216,751. Specific examples of alkyl mercapto acetic acidsuseful in accordance with the invention include amyl mercapto aceticacid, isooctyl mercapto acetic acid, lauryl mercapto acetic acid,hexadecyl mercapto acetic acid and the like. The thioethers having mixedalkyl groups derived from coconut oil, tallow fat, soy bean oil andsimilar naturally occurring materials are preferred. Lorol mercaptoacetic acid, for example, may be derived from a mixture of aliphaticmercaptides prepared from Lorol alcohols and may contain alkyl groups offrom 10 to 18 carbon atoms as follows:

Wt. Percent Similar mixed alkyl thioethers derived from other commercialmixtures of aliphatic compounds will be familiar to those skilled in theart.

Alkyl thioethers derived from other low molecular Weight carboxylicacids may also be useful in accordance with the invention.

The tetra-aliphatic ammonium salts of hydroxy carboxylic acids describedabove are added to hydrocarbons boiling in the range between about 75 F.and about 750 F. in accordance with the invention in concentrationsbetween about 0.00005 by weight and about 0.5% by weight. Concentrationsbetween about 0.0005 by weight and about 0.0.5 by weight are preferred.The alkyl acid phosphates and alkyl mercapto acetic acids which areemployed in conjunction with the tetra-aliphatic ammonium salts ofhydroxy carboxylic acids may be used in concentrations ranging fromabout 0.00005% by weight to about 0.5% by weight and are particularlyeffective in concentrations between about 0.001% by weight and about0.05% by weight. The :eight ratio between the tetra-aliphatic ammoniumsalts and the alkyl acid phosphates or alkyl mercapto acetic acids maybe varied widely, from about 0.1/1 to about 10.0/1 for example, but ingeneral it is preferred to employ from about 1 to about 4 parts of thetetra-aliphatic ammonium salt per part of the phosphate or of themercapto acetic acid.

The hydrocarbon oils boiling in the range between about 75 F. and about750 F. in which the additives of the invention may advantageously beemployed include petroleum distillate fuels, solvents, transformer oils,and the like. The additives are particularly useful in distillate fuelsincluding gasolines, aviation turbo-jet fuels, kerosenes, diesel fuelsand heating oils. Gasolines which may be benefitted by the presence ofthe additives include both motor gasolines and aviation gasolines suchas those defined by ASTM Specification D-910-56 and D-43956T. Suchgasolines may contain a wide variety of other additives such asanti-knock agents, scavenger agents, antioxidants, dyes, anti-icingagents, solvent oils and the like.

The boiling range of such gasolines normally extends between about 75 F.and about 450 F. As pointed out heretofore, the additives of theinvention are particularly useful in aviation turbo-jet fuels.Specifications for such fuels are set forth in U.S. MilitarySpecifications MIL-F- 5616, MIL-F-5624D, MILF-25524A and MIL-F- 25558A.These fuels are normally distillable at temperatures between about 100F. and about 600 F. Diesel fuels as referred to in connection with theinvention in general boil between about 250 F. and about 750 F. and aredefined at length in ASTM Specification D975- 53T. Heating oils withinwhich the additives may be incorporated include those set forth in ASTMSpecification D-396 48T, particularly those falling within grades 1 and2 of the specification. The additives may also be employed in purehydrocarbons and in other combustible volatile organic compounds of lowelectrical conductivity, carbon disulfide for example.

If desired, the additive agents of the invention may be incorporatedinto distillate fuels and other volatile combustible organic liquids inthe form of a concentrate comprising a tetraaliphatic ammonium salt of ahydroxycar boxylic acid; an acidic compound selected from the groupconsisting of alkyl acid phosphates and alkyl mercapto acetic acids; anda volatile inert organic solvent such as benzene, xylene, toluene,diethylene glycol, pyridine, or the like. A typical concentratecomposition is as follows:

It will be understood that the ratio of the tetraaliphatic ammonium saltand the acidic constituent in such concentrates may be varied within thelimits set forth above, from about 0.1 to about 10 parts of the ammoniumsalt per part of the phosphate or mercapto acetic acid, and that thepercentage of active ingredients in the concentrate may range from about10% up to about 90% by weight or more. Other additive agents such'asanti-oxidants, dyes, haze suppressors and the like may also be includedin the concentrates.

The exact nature and objects of the invention may be more fullyunderstood from the following examples.

EXAMPLE 1 In order to demonstrate the effectiveness of the additiveagents of the invention for improving the electrical properties ofhydrocarbon oils, tests were carried out to determine the specificconductivity of samples 'of aviation turbo-jet fuels, samples of thesame'fuels containing the individual additive constituents, and samplesof the fuels containing the additive constituents in combination. :Thefuels which were employed were representative of the fuels classified asJP-4 fuels and defined by-U.S. Military Specification MlL-F-5624D. Theyhad API gravities of about 48.7, Reid vapor pressures of about 2.5pounds per square inch and boiling ranges of from about 100 to about 520F. The additive constituents employed in the test were di-trimethylsoyaammonium malate, trimethylsoya "ammonium gluconate, tn'methylsoyaammonium lactate, lorol mercapto acetic acid, and a mixture of equalquantities of monoand di-octyl acid phosphates.

The specific conductivity of each of the samples tested was measured byapplying a fixed direct current voltage to a standard conductivity cellcontaining the sample. A

standard high-resistance element was connected in series with the celland the current which flowed in the circuit during each test was.computed by measuring the voltage across this resistance'element andapplying Ohms law. The resistance of the sample, the specific resistanceand the specific conductivity were in turn calculated. The

' ditions which could result in an explosion as are un- A resultsobtained in these .tests are shown in Table II below. r

TABLE II Synergistic efi'ect of additives upon specific COHdHCIWiIy'Specific Oon- Ratio (Base+ Composition ductivity r, (T Additives) Imho/cm. to :7 Base Base Fuel A 4. 5X10- Base Fuel A +0.005 Wt. PercentOetyl Acid Phosphate 4.4)(10- 1.0 Base Fuel A +0.005 Wt. Percent DIIrimethylsoya Ammonium Malate 2.3)(10- 5.1 Base Fuel A +0.0005 Wt.Percent Octyl Acid Phosphate +0.0045 Wt. Percent Di-TrimcthylsoyaAmmonium Malate 3. 9X10- 8. 7 Base Fuel A +0.001 Wt. Percent Octyi AcidPhosphate +0.004' Wt. Percent Di- Trimethylsoyn Ammonium Malete. 6. 7X1015 Base Fuel A +0.0025 Wt. Percent Octyl Acid Phosphate +0.0025-Wt.Percent Di-Trimethylsoya Ammonium Malate 5. 5X10" 12 Base Fuel A +0.01Wt. Percent Oetyl Acid Phosphate 4. 7x10- 1. 0 Base Fuel A +0.01 Wt.Percent Di-Trimethylsoya Ammonium Malate 3. 0X10- 6. 7

' Base Fuel A +0.001 Wt. Percent Octyl Acid Phosphate +0.009 Wt. PercentDi- Trimethylsoya Ammonium Malata. 7. 0X10- 16 Base Fuel A +0.002 Wt.Percent Octyl Acid Phosphate +0008 Wt. Percent D1- TrimethylsoyaAmmonium Malate 1.4)(10- 31 Base Fuel A +0.005 Wt. Percent Octyl AcidPhosphate +0.005 Wt. Percent Di- Trimethylsoya Ammonium Malate. 1. 2X10-27 Base Fuel B 1. 3X10' Base Fuel B+0.01 Wt Percent OctylAcid Phosphete.3.3)(10- 25 Base Fuel B +0.01 Wt. Percent imethylsoya. AmmoniumGluconate 5. 'i 10- 415 Base Fuel B +0.005 Wt. Percent Octyl AcidPhosphate +0.005 Wt. Percent Trimethylsoya Ammonium Gluconate- 1. 9X10-1, 462 Base FuelO 3.0X10- Base Fuel 0 +0.01 Wt. Percent Lorol I MercaptoAcetic Acid 6.5)(10- 2. 2 Base Fuel G +0.01 Wt. Percent D methylsoyaAmmonium Malate 8. 6X10" 9. 0 Base Fuel 0 +0005 Wt. Percent LorolMercapto Acetic Acid +0.005 Wt. Percent Di-Trimethylsoya Ammonium a1ata1.1 X10" 37 Base Fuel D 1.6)(10-" Base Fuel D +0.01 Wt. ercent Mon OctylAcid Phosphate 4.6)(10- 2. 9 Base fuel I) +0.01 Wt. Percent;Trimethylsoya Ammonium Lactate. 2. 9X10 1.8 Base Fuel D +0.005 Wt.Percent Mono- Di-Octyl Acid Phosphate +0.005 Wt.

Percent Trimethylspya Ammonium Lactate 1.,2X10? 75 The data in Table IIdemonstrate that the tetra-aliphatic ammonium salts of hydroxycarboxylic acids coact With the acid phosphates and mercapto aceticacids to produce a much greater increase in specific conductivity thancan be obtained when the constituents are employed individually." Theimprovement in specific conductivity" was particularly pronounced inthecase of fuel B, which had .an' extremely low conductivity initially,'butsyn-,

ergism between the additive constituents was manifested A in everyinstance. It can'be seen that fuels containing the combination additiveshave a'greatly reduced tend-i ency to accumulate electrical chargesthereinand thus are not as likely to discharge electrical energyunderconinhibitedfuels' and fuels containing the individual additives. 1 7

EXAMPLE 2 Tests similar to those described in the. preceding examplewere carried out by adding varying amounts of di-trimethyloleyl ammoniummalate and a mixture; of: equal parts of monoand di-octyl acid phosphateto ples of an aviation turbo-jet fuel. v x i l r The specificconductivities of the samples and the ratios between the conductivitiesof the samples containing the additive and that of the base fuel wereagain obtained. Table III sets forth these results. 1'

7 TABLE n1 Synergistic effect of additives upon specific conductivity ofaviation turbo-jet fuel Wt. Percent Additive in Fuel Specific RatioConductiv- (Base+ Di-Triity, c, a Addinlethyl Octyl Acid Inho/cm. tives)to oleyl Ani- Phosphate l1 Base momum Malate l 1 0 3. 9X10 0 0.013.7)(10 0.95 0.01 0 3. 5Xl0' 0 0. 0075 0. 0025 7. 7X10- 20 0.005 0.0053. 8X10 10 0.0025 0. 0075 2. 5X10 6. 4

1 Base Fuel.

Again it can be seen that the combination of the tetra-aliphaticammonium salt and the alkyl acid phosphate produced an increase inspecific conductivity which was surprisingly greater than that whichresulted from use of the individual additives. The use of 3 parts ofditrimethyloleyl ammonium malate and 1 part of octyl acid phosphate wasparticularly eifective and resulted in a -fold increase in specificconductivity.

EXAMPLE 3 In order to determine the extent to which the additiveconstituents are extracted from hydrocarbons in the presence of water,tests were carried out by determining the specific conductivities ofsamples of an aviation turbojet fuel and samples of the same fuelcontaining the additives. These samples were then extracted with waterand the conductivity values were again determined. A decrease inconductivity would indicate that the additive constituents wereextracted. The tests were carried out using a fuel similar to thatemployed in Example 1. The water extraction step involved shaking 80 cc.of the fuel and 20 cc. of water for 2 minutes and then allowing them tostand overnight. Results of these tests are set forth in Table IV.

Although the use of 0.01 wt. percent of di-trimethylsoya ammonium malateappreciably increases the conductivity of aviation turbo-jet fuels andsimilar hydrocarbon oils, data in the above table show that the benefitsof this increased conductivity may be lost if the oil is subsequentlyextracted with water. The conductivity of the sample containing only themalate in the above table was actually lower than that of the base fuelafter water extraction. The sample containing both the malate and thephosphate, on the other hand, had a higher conductivity than that of thesample containing only the malate before water extraction did notundergo any appreciable decrease in conductivity as a result of theextraction step. The additives of the invention are thus clearlysuperior to the salts of hydroxy carboxylic acids alone.

EXAMPLE 4 It is known that the presence of small amounts of water inaviation turbo-jet fuels, keroscnes, heating oils and similarhydrocarbon oil compositions tend to accelerate the generation andaccumulation of electrical charges in such compositions. It has beenfound, for example, that an oil saturated with water will produce twiceas many 7000 volt electrical discharges during laboratory pumping testsas will an anhydrous sample of the same oil. If small amounts ofdispersed Water are present in addition to the water of saturation, thenumber of discharges produced is even higher. For this reason, the watertolerance of such oils is extremely important. Many of the additivematerials which have been suggested for improving the electricalproperties of oils are highly surface-active materials and have anextremely adverse eifect upon water tolerance. The increasedconductivity efiected by such additives may to a considerable extent beoffset by their tendency to promote the suspension of dispersed water inthe oil to which they are added.

In order to determine the effect of the additives of the invention uponthe water tolerance of oils to which they are added, water tolerancestudies were carried out on samples of two different aviation turbo-jetfuels, samples of the same fuels to which had been addeddi-trimethylsoya ammonium malate and samples containing the ma]- ate andsmall amounts of octyl acid phosphate. The test employed is described inFederal Test Standard No. 791, Method 3251.6, Interaction of Water inAircraft Fuel. In brief, this test comprises shaking 80 cc. of the fuelto be tested and 20 cc. of water for a 2 minute period and then allowingthe mixture to settle for 5 minutes. At the end of the settling period,the condition of the water-fuel interface is noted. An interface ratingis assigned in accordance with the following criteria:

Interaction of water and aircraft fuels [Method 3251.0, Fed. Test Std.No. 791} Appearance of Interface Interface Rating Clear and clean A fewsmall clcar bubbles covering not more than Shred of lace and/or film atinterface.-- Loose lace and/or slight scum Tight lace and/or heavy scumThe condition of the fuel layer and the water layer on either side ofthe interface are also examined. An interface rating of 1 or 1B, with nosign of haze or emulsion in the fuel or water layers, is a passingrating and meets the requirements of the military specificationsgoverning the water tolerance of aviation turbo-jet fuels. The resultsobtained in tests of the additives of the invention are set forth inTable V.

It will be noted that the addition of di-trimethylsoya ammonium malatealone to base fuel A reduced the interface rating from a passing ratingof 1 to an unacceptable rating of 2. When 0.005 wt. percent of octylacid phosphate was employed with the same quantity of di-trimethylsoyaammonium malate, a satisfactory rating of 1B resulted. Samples of BaseFuel B containing both the octyl acid phosphate and the di-trimethylsoyaammonium malate had the same interface rating as did the base fuelcontaining no additive at all. The additive composition of the inventionthus meets the critical water tolerance requirements for additivesdesigned to improve the electrical properties of hydrocarbon oils.

EXAMPLE 5 A further critical requirement imposed upon aviation turbo-jetfuels and many other distillate petroleum products is that they must notexhibit a pronounced tendency to promote the rust and corrosion ofmetallic surfaces with which they come into contact in the presence ofsmall amounts of water. Military Specification MIL-F- 5624D prescribesthe use of certain rust inhibitors in turbo-jet fuels. It has been foundthat the additive combination of the present invention not only improvesthe electrical properties and water tolerance of such fuels but also isa potent rust inhibitor. In order to demonstrate this, tests werecarried out on samples of a turbo-jet fuel containing two differentcommercial rust inhibitors and samples of the same fuel containing theadditive combination of the invention. The test used was Modification Bof ASTM D665. In brief, thistest is carried out by immersing a highlypolished steel specimen in a vessel containing 300 cc. of oil and 30 cc.of water and agitating the oil-water mixture for a period of 24 hourswhile maintaining the temperature at 100" F. by thermostatic control.After the 24 hour period, the specimen is removed from the mixture,washed with a light hydrocarbon solvent and examined for corrosion. Theresults obtained with these tests are shown in Table VI.

7 TABLE VI Additive rust inhibiting properties Composition Percent RustTurbo-Jet Fuel +0.002 Wt. Percent Commercial Additive A 1 100 Turbo-JetFuel +0.003 Wt. Percent Commercial Additive B 2 10 An alkyl coco aminephos hate marketed commercially as a. corrosion inhibitor, descri ed inBelgian Patent 541,762.

A commercial rust inhibitor approved by the milltar services for use inaviation turbo-jet fuels and consisting pr marily ofa dimer of linoleicacid with a minor amount of an alkyl amine phosphate.

Commercial Additive A employed inthe testsreferred to above and inTableVI was an alkyl coco amine phosphate which is widely marketed as acorrosion inhibitor for use in gasolines and similar hydrocarboncompositions. Commercial Additive B was a commercial additive whichhasbeen approved by the military services for use in aviation turbo-jetfuels and is listed as a satisfactory inhibitor inMilitaryPSpecification MIL-F- 5624D. It will be notedthat neither ofthese twocomtion thus providesv an improved multi-functional additivewhich may be employed in-lieu of a multitude of 'sepaf 4 i 75 rateadditives which have been usedfheretoforejg EXAMPLE 6' A diesel fuelboiling in the range between about i i F. and about 600 F. is improvedwith respect to its elec-' EXAMPLE 8 A kerosene boiling in the rangebetween 300 and about 570 F. contains 0.02 wt. percent of C -oxo acidphosphate and 0.007 wt. percent of trimethylsoya ammonium gluconate. I

It will be understood that the additives of the present invention may beincluded into fuel, solvents and other hydrocarbon oils boiling in therange between about F. and about 750 F. in conjunction with a widevariety of other additives designed'to improve properties not affectedby the additives of the invention. Such other additives include, forexample, polymeric dispersant stabilizing additives, haze inhibitors,dyes, dye stabilizers and the like.

What is claimed is: a

1. A hydrocarbon oil boiling in the range between about 75 F. and about750 F. to which has been added from about 0.00005% to about'0.5% byweight of a tetra-acyclic aliphatic ammonium salt of an unsubstituted Cto C hydroxy carboxylic acid, the acyclic aliphatic groups of said saltselected from the class consisting of alkyl and alkenyl radicals eachradical containing from 1 to about 24 carbon atoms, and from about0.00005 to about 0.5% by weight of an acidic compound selected from thegroup consisting of alkyl acid phosphates in which the alkyl radicalseach contain from about 6 to about 10 carbon atoms and alkyl mercaptoacetic acids having alkyl groups containing from 4 to' 20 carbon atoms.

2. An oil as defined by claim 1 wherein said. tetraacyclic aliphaticammonium salt is a tetraalkyl ammonium salt of a C to C unsubstitutedaliphatic hydroxy' carbox'ylic acid.

3. An oil as defined by claim 1 whereinsaid acidic compound is anisooctyl acid phosphate. g

4. An oil as defined by claim 1 wherein said acidic compound is an alkylmercapto acetic acid having alkyl groups of from about 8 to about 18carbon atoms.

5. An oil as defined by claim- 1 wherein said tetraby weight and saidacidic compound is present in a concentration between about 0.001% andabout 0.05% by weight.

' 6. A liquid hydrocarbon fuel boiling in the range between about 75 F.and about 750? F. to which has been added from about 0.001% to about0.05% jby 7 weight of a tetra-acyclic aliphatic ammonium salt of an]unsubstituted C to C aliphatic hydroxy carboxylic acid; the aliphaticgroups of said saltselected from the class consisting of alkyl andalkenyl radicals each radical taining from 1 to about 24 carbon atoms,and from about r 0.001% to about 0.01% by weight of an alkyl acidphosphate in which the alkyl radicals each contain from about 6 to about'10 carbon-atoms. a 1 7. A fuel as defined by claim 6 wherein saidacid]: phosphate is a .monodi-alkyl acid phosphate. t

8. A fuel as defined by claim 6 wherein said ammonis um. salt is atrimethylsoya ammonium Salt. 7

9. A fuel as: defined'byclairn owherein said i um salt is-a malate; I

10. A fuel as defined by claim 6 wherein said ammonium salt isdi-trimethylsoya ammonium malate.

11. A fuel as defined by claim 6 wherein said alkyl acid phosphate is aC -oxo acid phosphate.

12. A liquid petroleum distillate turbo-jet engine fuel havingincorporated therein from about 0.0005% to about 0.05% by Weight ofdi-trimethylsoya ammonium malate and from about 0.001% to about 0.05% byweight of an octyl acid phosphate.

13. A liquid petroleum distillate turbo-jet engine fuel havingincorporated therein from about 0.0005% to about 0.05% by weight ofdi-trimethyl oleo ammonium malate and from about 0.001% to about 0.05%by weight of an octyl acid phosphate.

14. A liquid petroleum distillate turbo-jet engine fuel havingincorporated therein from about 0.0005% to about 0.05 by weight oftrimethylsoya ammonium gluconate and from about 0.001% to about 0.05% byweight of a mixture of alkyl mercapto acetic acids having alkyl groupsof from about 8 to about 18 carbon atoms.

15. An additive composition for improving the electrical properties ofcombustible liquid hydrocarbon fuels boiling between about 75 and 750 F.consisting essentially of 1 part of a tetra-acyclic aliphatic ammoniumsalt of an unsubstituted C to C hydroxy carboxylic acid having acylicaliphatic groups selected from the class consisting of alkyl and alkenylradicals of from 1 to 24- carbon atoms in length and from about 0.1 toabout 10 parts by weight of an acidic compound selected from the groupconsisting of alkyl acid phosphates wherein the alkyl groups eachcontain from about 6 to about 10 carbon atoms and alkyl mercapto aceticacids having alkyl groups containing from 4 to 20 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS

1. A HYDROCARBON OIL BOILING IN THE RANGE BETWEEN ABOUT 75*F. AND ABOUT750*F. TO WHICH HAS BEEN ADDED FROM ABOUT 0.00005% TO ABOUT 0.5% BYWEIGHT OF A TETRA-ACYCLIC ALIPHATIC AMMONIUM SALT OF AN UNSUBSTITUTED C2TO C10 HYDROXY CARBOXYLIC ACID, THE ACYCLIC ALIPHATIC GROUPS OF SAIDSALT SELECTED FROM THE CLASS CONSISTING OF ALKYL AND ALKENYL RADICALSEACH RADICAL CONTAINING FROM 1 TO ABOUT 24 CARBON ATOMS, AND FROM ABOUT0.00005% TO ABOUT 0.5% BY WEIGHT OF AN ACIDIC COMPOUND SELECTED FROM THEGROUP CONSISTING OF ALKYL ACID PHOSPHATES IN WHICH THE ALKYL RADICALSEACH CONTAIN FROM ABOUT 6 TO ABOUT 10 CARBON ATOMS AND ALKYL MERCAPTOACETIC ACIDS HAVING ALKYL GROUPS CONTAINING FROM 4 TO 20 CARBON ATOMS.